The present invention relates to a vernier caliper with unique features in the construction of its main beam.
The main beam in the conventional vernier calipers usually consists of a main beam body made from thin plate material with an external jaw and an internal jaw formed integral with the main beam body. The main beam is made by punching out a sheet metal blank roughly to its shape with a press machine; then machining and grinding the blank.
But the main beam made in this way has to be machined on all its faces; and because its shape is complicated because of the external jaw and the internal jaw on it, and since the main beam is made of highly wear-resistant metal, machining of the main beam body is difficult and laborious. Furthermore, because the metal of the main beam body is relatively thin, there developed the problem of warpage of the body that is caused by the heat generated in the machining. There has been also the problem in the conventional vernier calipers that error in reading the measured value is liable to develop because, in order to fit the vernier on the main beam body to slide, some play is provided between them in the directions of the plate thickness and width of the main beam.